Digital 50Hz/60Hz Freq Converter: OK to supply digital camera and remote feed welding head?

[racookpe1978]

We are reviewing a proposal to use a digital frequency converter to allow use of our (existing) remote feed wire welding machine (digital controlled camera, welding feed motor, and robot-like welding head positioner) off of the customer's power supplies in China.

I have had mixed results trying to run a very large 60 cycle pump motor from a 50/60 frequency converter in Europe, but believe that was due to a combination of (1) a too-small power supply (not enough startup current margin) and (2) not testing a slow-start pump motor requiring that motor to draw a larger current for a longer time than expected.

Has any one found troubles with the digital (square wave or modified square wave) frequency converter causing interferences with a digitally-controlled robot arm and camera?

Any other problems I have not thought of that some body else has had to solve?

 

[ScottyUK]

The electronics in the camera supply probably won't care about frequency, and the robot probably won't either, because they'll convert to a DC supply straight away. The motor - that depends on what type it is.

 

[itsmoked]

How big is the pump motor. BTW I concur with all of Scotties points.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

OP is planning to use a frequency converter, so the issue / question is the waveform.

If it's a big project, or one keeps getting involved in such projects, then perhaps one should install a permanent 50 Hz power source for commissioning such systems before shipment. For example: Our facility has 400 Hz aircraft power run throughout the building. It would be reasonable to have a big 50 Hz power source on site for testing, to avoid mixed results on site.

 

[ScottyUK]

One thing to consider is that some switching supplies try to draw a current matching the voltage in order to keep a decent power factor. That won't be happy on a square or quasi-sine waveform.

 

[racookpe1978]

Couple of answers and additions - My thanks to all who replied.

1. The pump was a large one, sized to drive a horizontal single stage centrifugal pump pushing 1200 gpm at 60 Hz, but I don't have the actual HP/KW on hand tonight. It was separate project (for Europe) from this one on the welding machine.

2. I agree that the welding feed (the robot arm control and motor and electronics) and the camera motor and camera will almost certainly be driven by DC, rectified from the source AC power. But the "cleanliness of that DC is what i am concerned about. Would a commercial UPS-type PC power supply reduce the potential for control problems in that whole system? The weld wire feed itself is separate, but again, that too may be affected.